1-Do you think it's more preferable I build (yes I want to build it) a new amp, or can I just build a pre-amp? This amp works very well so if it’s possible I'd like to keep using it. 2-Which amp or pre-amp do you recommend me?
Constraints imposed: *I'm not scared about soldering but I am not very reassured at the idea of starting from a simple assembly plan and having to find all the parts by myself. I would prefer a kit. I have nothing to make a PCB so... **About price range: The best value for less than 100€ (by not taking into account the housing, cables... Just the AMP/Pre-AMP and its PSU). ***I don't want to add a card directly on my boss player. It will be in a separate case with its own PSU. ****(EDIT): I adjust the volume via Volumio. The volume of the amp remains fixed (more or less).
Typical domestic listening is done at quite low power levels, 1 watt or so. There is no sensitivity figure given for the complete loudspeaker you are constructing, but the tweeter has a sensitivity of 90 db @1 W @1 M, that isn't particularly high. It looks like the impedance of those speakers is 4 ohms, your amp is rated: 30 watts x 2 at 8 ohms [ 40 to 20KHz THD 0.005% ] 40W at 4 ohms Dynamic power: 50W / 80W at 8 / 4ohms
I'd be trying your new speakers on your existing amp before spending more money.